That's what we did in the latest build actually It will not start MLAT with the configuration other then receiver=dvbt and FR24's dump1090 fork (which is, again, a fork of Malcolm Robb's fork).
Those options are also removed from the signup wizard when MLAT is enabled.
Also the logging toggle has been fixed (it was unable to disable logging through signup wizard before).

I'd like just to clarify, the dump1090 that is bundled with fr24feed package now (https://github.com/Flightradar24/dump1090), is a fork of Malcom Robb's dump1090 fork, so you can still use all it's features, no need to drop MLAT
The modification made is intended to provide timestamps within messages as close to the originally receive timestamp as possible. That's why we require this particular dump1090 in order to run MLAT.

I currently feed both FA and FR24 from the one Pi; I just noticed vinnyspb mention is a fork of Malcom Robb's dump1090 fork in regards to dump1090....

I recieved an email from FA this week in regards to their MLAT setup, part of which said Aircraft being tracked with MLAT will be in blue on your local web interface hinting at possibly they are running a specific fork of dump1090 and the local html page.

Has any one got a dual setup running succesgully yet with the FR24 beta and FA's new setup?

I was about to write a bit about how I couldn't understand why it was happening... And then.. I thought of something.. .oO What if dhcp is assigning ntp servers Oo. And "ntpdc -c peers" confirmed this, and the server was really really slow.. It's still not syncing very quickly, a lot longer than the 10mins it stays sync'd for before it wants to check again... When it does sync there is no offset though which is good...

I've been using this double setup (FA & FR24) on one RPi2 since march and all was well up to today when I updated fr24feed to 1.0.14-5. Now I've got no feed to FR24.

FA works fine (PiAware pack), but fr24feed is not. Tried to remove it and install again, run wizard one more time and still nothing. :8754 webpage is not working either.

EDIT:

Ok, after 2 reboots it looks like this:

So changed from Active (Exiting) to (running). But still not online on feed page and no config page.

Here is another one:

But still no success.

I hope I am not breaking a cardinal rule by talking about other feeders

You have to let the fr24feeder and it's version of dump1090 start first. Then the FA feeder can connect to the same dump1090, but you need to configure FA's MLAT beta so it doesn't try and feed MLAT positions back to dump1090 if you go through their forum post for their Pi MLAT beta test it will tell you how to do this (it's in relation to viewing MLAT data in VRS without sending it into dump1090 for display on it's own webpage)...